1. Field of the Invention
The present invention relates to a process for producing chlorine from ammonium chloride and in particular relates to an integrated process for producing chlorine and sodium carbonate by taking the ammonium chloride produced in the Solvay process and converting it initially to a metal chloride and converting the metal chloride to chlorine by a fused salt electrolysis.
2. Description of the Prior Art
Most of the chlorine produced in the United States is generated from the electrolytic oxidation of sodium chloride (brine) solutions. The electrolysis of sodium chloride solutions produces sodium hydroxide, chlorine and hydrogen. This reaction is, of course, the basis of the chlor-alkali industry. The electrical energy consumed by this reaction accounts for about one-fourth the total energy used by the electrochemical industry and the latter accounts for about 7% of the total electrical energy generated in the United States. Diaphragm cells are used for about 80% of the present chlor-alkali production. The graphite anodes used in these cells suffer the disadvantage that they are gradually consumed in the electrolytic process. Dimensionally stable anodes are presently replacing graphite anodes but suffer from the disadvantage of being very expensive. Moreover, improvements in the chlor-alkali electrolysis over the past ten years have only resulted in a drop in the electrical requirements of from 4.1 to 3.8 volts or from 1.4 to 1.3 kwh/lb of chlorine.
The Solvay process has long been utilized to produce sodium carbonate. In the process, ammonium chloride is reacted with calcium oxide to produce calcium chloride, ammonia and water. Calcium chloride is the only by-product of the Solvay process. It is a compound of limited commercial importance, however, and thus substantial amounts must be disposed of thereby resulting in environmental problems.